docs: def batch_per(hyps: Sequence[Sequence[T]],
                refs: Sequence[Sequence[T]]) -> float:
      """ Calculates the phoneme error rate of a batch."""
  
      macro_per = 0.0
      for i in range(len(hyps)):
          ref = [phn_i for phn_i in refs[i] if phn_i != 0]
          hyp = [phn_i for phn_i in hyps[i] if phn_i != 0]
          macro_per += distance.edit_distance(ref, hyp)/len(ref)
      return macro_per/len(hyps)